That the LEP tunnel should be built with a future hadron collider in mind was a given by the end of the decade. But there had also been proposals to build large proton storage rings, or re-equip the ISR with superconducting magnets. Some had people suggesting building an electron-proton collider at CERN, and there were ambitious plans looking far into the future at a possible Very Big Accelerator to be built somewhere in the world, which went by its acronym VBA. For the field of particle physics, with its very long lead times, this is part of the normal cycle, and while most of those options never came to fruition, this process did pave the way for the LHC. Today, with the LHC programme underway, the time has come for CERN to start seriously considering the options for its post-LHC future.

Perhaps the best known of those options is a linear collider, either at CERN or elsewhere, but it’s not the only one. Another was identified by the recent European Strategy update, which includes a recommendation to carry out a vigorous accelerator R&D programme with an emphasis on hadron or lepton high-energy frontier machines. With this in mind, we are launching a five-year international design study to investigate the potential for Future Circular Colliders, the FCC study, which will put the emphasis on a hadron collider with a collision energy of 100 TeV housed in a tunnel 80-100 km around. This will complement the on-going linear collider studies, which are already well established.

The FCC study will also look at the potential for a lepton collider of the same size as an intermediate step, and it will examine the lepton-hadron option. All of these possible routes have their proponents, and informal working groups have already been established under the names of VHE-LHC for the hadron machine, TLEP for the lepton machine and VLHeC for the lepton-hadron collider. The FCC study brings them together in a formal framework, and has been fixed at five years in order to provide input to the next European Strategy update, scheduled for 2018. It will kick-off with a meeting hosted by CERN in February, the details of which can be found on Indico.

In common with the VBA initiative of the 1970s, the FCC study will look at all the possible options for a circular tunnel, although the priority will be for a hadron machine. There’s also another very important thing the two initiatives share: they recognise that Europe cannot do this alone. That’s why we’re inviting colleagues from around the world to join us in February, to help us begin the process that will lead to one potential new chapter in the global development of particle physics.